.before-art-main{
	width: 80%;
	margin: 0 auto;
}
.art-main-item{
	margin: 10px 0;
	font-size: 1.2em;
	font-weight: 500;
}
.art-main-item .first-child-item{
	margin:10px 0;
	margin-left: 30px;
	font-size: 1em;
	font-size: 400;
}
.art-main-item .next-child-item{
	margin:10px 0;
	margin-left: 60px;
	font-size: 1em;
	font-size: 400;
}
.chengeng{
	width: 60%;
	margin: 0 auto;
	text-align: center;
}
.chengeng img{
	width: 100%;
	height: 400px;
}
.jieshao-main{
	width: 80%
	margin: 0 auto;
	margin-top: 30px;
}
.back-act{
	 width: 149px;
    height: 200px;
    margin-left: 60px;
    margin-bottom: 10px;
}